DOES CLIMATIC WARMING INCREASE THE RISK OF FROST DAMAGE IN NORTHERN TREES

The effect of climatic warming on the timing of bud burst and the subsequent risk of frost damage on trees in central Finland was assessed with the aid of a computer model, 73 years of temperature data and a climatic scenario corresponding to doubled level of atmospheric CO2. In general, climatic warming hastened bud burst, due to ontogenetic development during warm spells in autumn, winter and spring. During the years with the warmest winters in the scenario conditions: (a) bud burst took place during mid-winter; and (2) depending on the year, the trees were subsequently exposed to temperatures between -27 and -10-degrees-C. This finding suggests that the risk of frost damage to trees will be increased if the predicted climatic warming occurs. Because of the assumptions used in the model, the results are not conclusive, but they do point out the importance of further experimental studies on genetic and environmental regulation of timing of bud burst in trees.